Death or its danger is a plot device in many, if not most, stories period. Spock died and then didn't back in TOS, before the Wrath of Khan (which was actually a sequel to an episode named "Space Seed"). Read Asomov's robot stories (The Complete Robot) from the 30s and 40s, most had death or threat of death in their plots. The very first story in I, Robot had a robot saving a little girl's life. Hell, the old Flash Gordon shows from the thirties had cliffhangers with threats of death every single week!